An inkjet printhead is a device for printing a predetermined color image by ejecting minute droplets of ink on a desired area of a printing paper. Inkjet printheads may be generally classified into two types according to the ejection mechanism of ink droplets. The first type is a thermal inkjet printhead that ejects ink droplets using the expansion force of ink bubbles created using a heat source, and the second type is a piezoelectric inkjet printhead that ejects inkjet droplets using a pressure created by the deformation of a piezoelectric element.
For the ejection mechanism of ink droplets of a thermal inkjet printhead, a pulse type current is applied to a heater composed of a heating resistor, and ink around the heater is instantly heated to approximately 300° C. Thus, the ink boils, and an ink bubble is generated. The expansion of the ink bubble applies pressure to the ink filled in the ink chamber. As a result, ink is ejected from the ink chamber to the outside through nozzle in the form of droplet.